FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_clock.c
1 /*-
2 * Copyright (c) 1988 University of Utah.
3 * Copyright (c) 1982, 1990, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * the Systems Programming Group of the University of Utah Computer
8 * Science Department.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 4. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * from: Utah $Hdr: clock.c 1.18 91/01/21$
35 * from: @(#)clock.c 8.2 (Berkeley) 1/12/94
36 * from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
37 * and
38 * from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
39 */
40
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD$");
43
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/kernel.h>
47 #include <sys/bus.h>
48 #include <sys/clock.h>
49 #include <sys/limits.h>
50 #include <sys/sysctl.h>
51 #include <sys/timetc.h>
52
53 int tz_minuteswest;
54 int tz_dsttime;
55
56 /*
57 * The adjkerntz and wall_cmos_clock sysctls are in the "machdep" sysctl
58 * namespace because they were misplaced there originally.
59 */
60 static int adjkerntz;
61 static int
62 sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS)
63 {
64 int error;
65 error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
66 if (!error && req->newptr)
67 resettodr();
68 return (error);
69 }
70 SYSCTL_PROC(_machdep, OID_AUTO, adjkerntz, CTLTYPE_INT | CTLFLAG_RW |
71 CTLFLAG_MPSAFE, &adjkerntz, 0, sysctl_machdep_adjkerntz, "I",
72 "Local offset from UTC in seconds");
73
74 static int ct_debug;
75 SYSCTL_INT(_debug, OID_AUTO, clocktime, CTLFLAG_RWTUN,
76 &ct_debug, 0, "Enable printing of clocktime debugging");
77
78 static int wall_cmos_clock;
79 SYSCTL_INT(_machdep, OID_AUTO, wall_cmos_clock, CTLFLAG_RW,
80 &wall_cmos_clock, 0, "Enables application of machdep.adjkerntz");
81
82 /*--------------------------------------------------------------------*
83 * Generic routines to convert between a POSIX date
84 * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
85 * Derived from NetBSD arch/hp300/hp300/clock.c
86 */
87
88
89 #define FEBRUARY 2
90 #define days_in_year(y) (leapyear(y) ? 366 : 365)
91 #define days_in_month(y, m) \
92 (month_days[(m) - 1] + (m == FEBRUARY ? leapyear(y) : 0))
93 /* Day of week. Days are counted from 1/1/1970, which was a Thursday */
94 #define day_of_week(days) (((days) + 4) % 7)
95
96 static const int month_days[12] = {
97 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
98 };
99
100 /*
101 * Optimization: using a precomputed count of days between POSIX_BASE_YEAR and
102 * some recent year avoids lots of unnecessary loop iterations in conversion.
103 * recent_base_days is the number of days before the start of recent_base_year.
104 */
105 static const int recent_base_year = 2017;
106 static const int recent_base_days = 17167;
107
108 /*
109 * Table to 'calculate' pow(10, 9 - nsdigits) via lookup of nsdigits.
110 * Before doing the lookup, the code asserts 0 <= nsdigits <= 9.
111 */
112 static u_int nsdivisors[] = {
113 1000000000, 100000000, 10000000, 1000000, 100000, 10000, 1000, 100, 10, 1
114 };
115
116 /*
117 * This inline avoids some unnecessary modulo operations
118 * as compared with the usual macro:
119 * ( ((year % 4) == 0 &&
120 * (year % 100) != 0) ||
121 * ((year % 400) == 0) )
122 * It is otherwise equivalent.
123 */
124 static int
125 leapyear(int year)
126 {
127 int rv = 0;
128
129 if ((year & 3) == 0) {
130 rv = 1;
131 if ((year % 100) == 0) {
132 rv = 0;
133 if ((year % 400) == 0)
134 rv = 1;
135 }
136 }
137 return (rv);
138 }
139
140 int
141 clock_ct_to_ts(const struct clocktime *ct, struct timespec *ts)
142 {
143 int i, year, days;
144
145 if (ct_debug) {
146 printf("ct_to_ts([");
147 clock_print_ct(ct, 9);
148 printf("])");
149 }
150
151 /*
152 * Many realtime clocks store the year as 2-digit BCD; pivot on 70 to
153 * determine century. Some clocks have a "century bit" and drivers do
154 * year += 100, so interpret values between 70-199 as relative to 1900.
155 */
156 year = ct->year;
157 if (year < 70)
158 year += 2000;
159 else if (year < 200)
160 year += 1900;
161
162 /* Sanity checks. */
163 if (ct->mon < 1 || ct->mon > 12 || ct->day < 1 ||
164 ct->day > days_in_month(year, ct->mon) ||
165 ct->hour > 23 || ct->min > 59 || ct->sec > 59 || year < 1970 ||
166 (sizeof(time_t) == 4 && year > 2037)) { /* time_t overflow */
167 if (ct_debug)
168 printf(" = EINVAL\n");
169 return (EINVAL);
170 }
171
172 /*
173 * Compute days since start of time
174 * First from years, then from months.
175 */
176 if (year >= recent_base_year) {
177 i = recent_base_year;
178 days = recent_base_days;
179 } else {
180 i = POSIX_BASE_YEAR;
181 days = 0;
182 }
183 for (; i < year; i++)
184 days += days_in_year(i);
185
186 /* Months */
187 for (i = 1; i < ct->mon; i++)
188 days += days_in_month(year, i);
189 days += (ct->day - 1);
190
191 ts->tv_sec = (((time_t)days * 24 + ct->hour) * 60 + ct->min) * 60 +
192 ct->sec;
193 ts->tv_nsec = ct->nsec;
194
195 if (ct_debug)
196 printf(" = %jd.%09ld\n", (intmax_t)ts->tv_sec, ts->tv_nsec);
197 return (0);
198 }
199
200 int
201 clock_bcd_to_ts(const struct bcd_clocktime *bct, struct timespec *ts, bool ampm)
202 {
203 struct clocktime ct;
204 int bcent, byear;
205
206 /*
207 * Year may come in as 2-digit or 4-digit BCD. Split the value into
208 * separate BCD century and year values for validation and conversion.
209 */
210 bcent = bct->year >> 8;
211 byear = bct->year & 0xff;
212
213 /*
214 * Ensure that all values are valid BCD numbers, to avoid assertions in
215 * the BCD-to-binary conversion routines. clock_ct_to_ts() will further
216 * validate the field ranges (such as 0 <= min <= 59) during conversion.
217 */
218 if (!validbcd(bcent) || !validbcd(byear) || !validbcd(bct->mon) ||
219 !validbcd(bct->day) || !validbcd(bct->hour) ||
220 !validbcd(bct->min) || !validbcd(bct->sec)) {
221 if (ct_debug)
222 printf("clock_bcd_to_ts: bad BCD: "
223 "[%04x-%02x-%02x %02x:%02x:%02x]\n",
224 bct->year, bct->mon, bct->day,
225 bct->hour, bct->min, bct->sec);
226 return (EINVAL);
227 }
228
229 ct.year = FROMBCD(byear) + FROMBCD(bcent) * 100;
230 ct.mon = FROMBCD(bct->mon);
231 ct.day = FROMBCD(bct->day);
232 ct.hour = FROMBCD(bct->hour);
233 ct.min = FROMBCD(bct->min);
234 ct.sec = FROMBCD(bct->sec);
235 ct.dow = bct->dow;
236 ct.nsec = bct->nsec;
237
238 /* If asked to handle am/pm, convert from 12hr+pmflag to 24hr. */
239 if (ampm) {
240 if (ct.hour == 12)
241 ct.hour = 0;
242 if (bct->ispm)
243 ct.hour += 12;
244 }
245
246 return (clock_ct_to_ts(&ct, ts));
247 }
248
249 void
250 clock_ts_to_ct(const struct timespec *ts, struct clocktime *ct)
251 {
252 int i, year, days;
253 time_t rsec; /* remainder seconds */
254 time_t secs;
255
256 secs = ts->tv_sec;
257 days = secs / SECDAY;
258 rsec = secs % SECDAY;
259
260 ct->dow = day_of_week(days);
261
262 /* Subtract out whole years. */
263 if (days >= recent_base_days) {
264 year = recent_base_year;
265 days -= recent_base_days;
266 } else {
267 year = POSIX_BASE_YEAR;
268 }
269 for (; days >= days_in_year(year); year++)
270 days -= days_in_year(year);
271 ct->year = year;
272
273 /* Subtract out whole months, counting them in i. */
274 for (i = 1; days >= days_in_month(year, i); i++)
275 days -= days_in_month(year, i);
276 ct->mon = i;
277
278 /* Days are what is left over (+1) from all that. */
279 ct->day = days + 1;
280
281 /* Hours, minutes, seconds are easy */
282 ct->hour = rsec / 3600;
283 rsec = rsec % 3600;
284 ct->min = rsec / 60;
285 rsec = rsec % 60;
286 ct->sec = rsec;
287 ct->nsec = ts->tv_nsec;
288 if (ct_debug) {
289 printf("ts_to_ct(%jd.%09ld) = [",
290 (intmax_t)ts->tv_sec, ts->tv_nsec);
291 clock_print_ct(ct, 9);
292 printf("]\n");
293 }
294 }
295
296 void
297 clock_ts_to_bcd(const struct timespec *ts, struct bcd_clocktime *bct, bool ampm)
298 {
299 struct clocktime ct;
300
301 clock_ts_to_ct(ts, &ct);
302
303 /* If asked to handle am/pm, convert from 24hr to 12hr+pmflag. */
304 bct->ispm = false;
305 if (ampm) {
306 if (ct.hour >= 12) {
307 ct.hour -= 12;
308 bct->ispm = true;
309 }
310 if (ct.hour == 0)
311 ct.hour = 12;
312 }
313
314 bct->year = TOBCD(ct.year % 100) | (TOBCD(ct.year / 100) << 8);
315 bct->mon = TOBCD(ct.mon);
316 bct->day = TOBCD(ct.day);
317 bct->hour = TOBCD(ct.hour);
318 bct->min = TOBCD(ct.min);
319 bct->sec = TOBCD(ct.sec);
320 bct->dow = ct.dow;
321 bct->nsec = ct.nsec;
322 }
323
324 void
325 clock_print_bcd(const struct bcd_clocktime *bct, int nsdigits)
326 {
327
328 KASSERT(nsdigits >= 0 && nsdigits <= 9, ("bad nsdigits %d", nsdigits));
329
330 if (nsdigits > 0) {
331 printf("%4.4x-%2.2x-%2.2x %2.2x:%2.2x:%2.2x.%*.*ld",
332 bct->year, bct->mon, bct->day,
333 bct->hour, bct->min, bct->sec,
334 nsdigits, nsdigits, bct->nsec / nsdivisors[nsdigits]);
335 } else {
336 printf("%4.4x-%2.2x-%2.2x %2.2x:%2.2x:%2.2x",
337 bct->year, bct->mon, bct->day,
338 bct->hour, bct->min, bct->sec);
339 }
340 }
341
342 void
343 clock_print_ct(const struct clocktime *ct, int nsdigits)
344 {
345
346 KASSERT(nsdigits >= 0 && nsdigits <= 9, ("bad nsdigits %d", nsdigits));
347
348 if (nsdigits > 0) {
349 printf("%04d-%02d-%02d %02d:%02d:%02d.%*.*ld",
350 ct->year, ct->mon, ct->day,
351 ct->hour, ct->min, ct->sec,
352 nsdigits, nsdigits, ct->nsec / nsdivisors[nsdigits]);
353 } else {
354 printf("%04d-%02d-%02d %02d:%02d:%02d",
355 ct->year, ct->mon, ct->day,
356 ct->hour, ct->min, ct->sec);
357 }
358 }
359
360 void
361 clock_print_ts(const struct timespec *ts, int nsdigits)
362 {
363 struct clocktime ct;
364
365 clock_ts_to_ct(ts, &ct);
366 clock_print_ct(&ct, nsdigits);
367 }
368
369 int
370 utc_offset(void)
371 {
372
373 return (tz_minuteswest * 60 + (wall_cmos_clock ? adjkerntz : 0));
374 }
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